Add EventManager

1 files changed, 86 insertions, 0 deletions

diff --git a/sphinx/events.py b/sphinx/events.py
new file mode 100644
index 000000000..ab31fe234
--- /dev/null
+++ b/sphinx/events.py
@@ -0,0 +1,86 @@
+# -*- coding: utf-8 -*-
+"""
+    sphinx.events
+    ~~~~~~~~~~~~~
+
+    Sphinx core events.
+
+    Gracefully adapted from the TextPress system by Armin.
+
+    :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+from __future__ import print_function
+
+from collections import defaultdict
+
+from six import itervalues
+
+from sphinx.errors import ExtensionError
+from sphinx.locale import _
+
+if False:
+    # For type annotation
+    from typing import Any, Callable, Dict, List  # NOQA
+
+
+# List of all known core events. Maps name to arguments description.
+core_events = {
+    'builder-inited': '',
+    'env-get-outdated': 'env, added, changed, removed',
+    'env-get-updated': 'env',
+    'env-purge-doc': 'env, docname',
+    'env-before-read-docs': 'env, docnames',
+    'source-read': 'docname, source text',
+    'doctree-read': 'the doctree before being pickled',
+    'env-merge-info': 'env, read docnames, other env instance',
+    'missing-reference': 'env, node, contnode',
+    'doctree-resolved': 'doctree, docname',
+    'env-updated': 'env',
+    'html-collect-pages': 'builder',
+    'html-page-context': 'pagename, context, doctree or None',
+    'build-finished': 'exception',
+}  # type: Dict[unicode, unicode]
+
+
+class EventManager(object):
+    def __init__(self):
+        # type: () -> None
+        self.events = core_events.copy()
+        self.listeners = defaultdict(dict)  # type: Dict[unicode, Dict[int, Callable]]
+        self.next_listener_id = 0
+
+    def add(self, name):
+        # type: (unicode) -> None
+        if name in self.events:
+            raise ExtensionError(_('Event %r already present') % name)
+        self.events[name] = ''
+
+    def connect(self, name, callback):
+        # type: (unicode, Callable) -> int
+        if name not in self.events:
+            raise ExtensionError(_('Unknown event name: %s') % name)
+
+        listener_id = self.next_listener_id
+        self.next_listener_id += 1
+        self.listeners[name][listener_id] = callback
+        return listener_id
+
+    def disconnect(self, listener_id):
+        # type: (int) -> None
+        for event in itervalues(self.listeners):
+            event.pop(listener_id, None)
+
+    def emit(self, name, *args):
+        # type: (unicode, Any) -> List
+        results = []
+        for callback in itervalues(self.listeners[name]):
+            results.append(callback(*args))
+        return results
+
+    def emit_firstresult(self, name, *args):
+        # type: (unicode, Any) -> Any
+        for result in self.emit(name, *args):
+            if result is not None:
+                return result
+        return None